Oil Cooler Dug into Cowling - with leaks (PICS)

[Apollo]

Ah yes, the joys of owning your own Mooney.

 

After a thunker of a landing, I was getting ready to put the airplane in the hangar. I looked down after getting the tow bar out. The mechanic near by said, boy thats a lot of oil, is that normal?

 

Oh shit. Immediately I think of all the bad landings I've ever done, and since I've been practicing in the right seat I immediately though I crashed the thing.

 

Next morning we took off the cowl to see what the matter was. I am expecting a destroyed nose...

 

 

Imagine taking off the pilot side cowl. Towards the bottom left hand side as you take the cowl off, is where these pictures are taken.

 

 

The first pic was taken right after the cowling was undone. (53 screws per cowl thanks mooney) You can see the oil cooler  vents (bottom) rubbing against the inside of the cowl.

The bottom pic is the two parts after they have been moved out of each others way. Check out that nice friction burn into the vents. They are ALL supposed to be rounded instead of.....shark toothed.






Only a 450 dollar fix from aircraftspruce.

I noticed it because oil was leaking from the nose onto the ground. Pretty steadily after it has been parked a second. of course, you always start wondering which landing you had that fucked it all up. Easy to second guess yourself. The mechanic absolved me of all sins and said it was just the previous mechanic that let them rub against each other. Sucks.

 

[N601RX]

Glad it didn't push all the oil out.  If your hoses are starting to get old, and need new ones it would be a good time to do the Lasar relocation kit and move the cooler to behind the #4 cylinder.

[jetdriven]

That chafing didnt happen in the last hour.  Was the cooler mounted to the cowling?  It looks like it moved about 3/4" to have that kind of wear.

[N601RX]

It also looks like it was possibly mounted with tinnerman nuts instead of AN nuts and bolts.

[BigTex]

How is that possible? Was the cowling bent or something come loose? I wonder if there was mod done that shaved off the fins of the cooler.

[N601RX]

I circled what looks like a Tinnerman nut to me.  I'm guessing it was mounted with sheet metal screws?

[jetdriven]

I dont see a screw sticking out of that tinnerman nut.  We got a Cherokee 140 in the shop the other day. new owner, fresh 7 grand annual  / prebuy at a prized Piper shop in Atlanta.  On the  flight home the landing light quits. We open it up to investigate, the wires are burned and arc'd in 3 places on the exhaust. The oil cooler was loose and I mean the only thing holding it was 1 AN3 bolt through a worn out tinnerman nutplate, and the oil hoses. They cut down AN970 fender washers and did all sorts of things, but it was totally hardware laying in the cowl.

[kerry]

WOW,  I frequently remove my cowling and inspect my power plant and never noticed my oil cooler that close to the baffle.  I'm certainly going to check again.  I do know of someone who just destroyed his airplane(not a mooney) earlier this month because of a blown out oil cooler.  Thanks for the pix.

[tomn]

I can't stress enough about the importance of learning what to look for and then looking for it each and every time anyone works on your plane. I have had numerous issues that were the result of mistakes made by mechanics working on the plane - some very serious. No good mechanic will be offended if you check behind him at least enough to be sure things look buttoned up properly. These are great people and we need them, but they are human and....

[Alan Fox]

I will sell you a used cooler for 125.00 ....Forget spruce....

[HRM]

Why it is unwise to use unauthorized parts in an airplane (afterword of "Grounded at KFDK")

(originally posted to MAPAlist)

 

 

On Saturday, October 13th, 2012, I flew my '66 M20E to Frederick (KFDK) Maryland from Beaumont (KBPT) Texas--with a fuel stop in Winchester Tennessee. I arrived at FDK at sunset, with plenty of light left to land without lighting. I parked the plane at a tie-down at Landmark Aviation and hurried to get to my niece's wedding, which had already started. The next morning around 10 AM I returned to the airport to fly home only to find two puddles of oil on the ground, a small one to the right of the nose wheel and a huge one under the left nose gear door. A thick stripe of oil marked the center of that door. I checked the oil level and found it to be 4 quarts, so at that point the flight was scrubbed.

 

Luckily my niece knew an A&P, which I found out later was at the wedding, and he came out at noon to see if he could determine where the oil was coming from. He traced it to the oil cooler ("RADIATOR, OIL" in the PM). When he removed the screws holding the cooler in place, he discovered that the top of it had been rubbing up against the cowling that forms the bottom section of the ovoid cowl opening that provides the main cooling air to the engine. While we were looking at the engine, I had noticed what looked to be small louvers in that cowling down inside the hole just above where the cooler is mounted. It turned out that those slits had been produced by the cooling fins of the cooler. 

 

A few weeks prior to this flight I had gone down to the hangar to check on the plane and had noticed some drops of oil on the nose wheel. Just a tiny bit and when I saw it I didn't think much of it. At my last annual, I was told by my IA that I had "the driest Lycoming he had ever seen" and he has quite a few decades with airplanes. I figured that my engine had finally decided to weep some oil. I think that was the point when the cooler was initially compromised by the sawing motion of the cooling fins against the cowling. What was astonishingly fortunate was the fact that I had made a six+ hour flight without going down or ruining the engine--and there were mountains involved.

 

So, the next step was to find a cooler. Since it was Sunday, all I could do was Internet search and appeal to fellow Mooniacs in preparation for ordering, or more hopefully fetching one the next day. Monday morning I called the nearest MSC that might have one and there was no joy. The main parts houses (Spruce, Chief, etc.) did not stock the coolers, so overnight was out of the question. Landmark called me at noon to say that they had one at one of their North Carolina facilities and could have it overnighted for $30. It turns out I could not have done any better with the price using one of the online parts houses. Pacific wanted $65, if memory serves, to overnight. Then the bad news...

 

The A&P who had diagnosed the problem for me Sunday wasn't available Tuesday for when the part would come in. I was at the mercy of Landmark, so I bit the bullet and told them to proceed with the install--and now comes the good part. The Landmark A&P discovered that the old cooler had been fitted with Rivnuts whereas the new one just had mounting flanges and bolt holes. He got suspicious and when he checked the parts list for my E, he discovered that the correct fasteners were AN3-4A's, which are significantly thicker than the 10-32 pan heads that were used with the Rivnuts! This is why the cooler drifted up and rubbed against the cowling. After he put the correct bolts in, he told me that there was about a 1/2" of clearance to the cowling and that the new cooler was not going anywhere. My E can be a nasty lady and she bit him good (I saw the blood) when he put the nuts and washers on the inner bolts. I am guessing that it was for this reason that someone put the Rivnuts on the cooler.

Back in the 70's there was an AD (77-08-06) where the cooler had to be inspected yearly. On my E, the cooler was last replaced in January of '82 under AD 77-18-1, so that may be when the Rivnutted cooler was installed. Who was the guilty party? The name is illegible in my logbook and may have done by an A&P two owners ago--or even one of the owners themselves. The failed cooler had been rebuilt twice, which is why I went for a brand new one. My sister-in-law asked me how this mod could have escaped almost 30 years of annuals, many by a top-ranked MSC. I told her that the cooler is no longer under an AD and on the checklist it simply states "Inspect condition of oil cooler." I imagine that most just check the protector screen and fins for debris, but only the sharpest-eyed of A&P's or IA's would have noticed the wrong fasteners and even then most likely would not have investigated. It was not until this problem that the deviation was discovered and that is the lesson of this story. On its face, the idea of Rivnuts on such an onerous to install part seems like a great idea, but the potential consequences of the mod could have exacted a terrible price, and I am not talking about an engine rebuild.

 

Harley

M20E Super 21 N5976Q @ KBPT

 

[final bill: 1.153 AMU]

[Apollo]

HRM, 

 

Thanks for finding and posting that story. It's incredible how I didn't notice it over the past 6 months. A little oil certainly seemed to be ' no big deal ' as it 'leaked within limits' and I didn't need to put excessive amounts of oil to do a cross country.

 

 

100% of my flights in my mooney are 150nm cross countries. I didn't initially think it was a big deal when we saw it after undoing the cowl, but the phrases of 'ruined engines' and 'glad you didn't die' are certainly sobering. 

[Apollo]

By the way, yes it was mounted with Tinneman nuts and sheet metal screws.........................WOW

[Apollo]

New oil cooler installed, Airplane PURRS like a kitten now. Something just seems happier. Oil pressure was a little higher overall now, and the CHT's and oil temps are now much lower on the analog gauges. Will continue to monitor and report back.

 

 

 

They had to fabricate a bracket to make it lower, now i've got more than 1/3rd inch clearance and it looks great!

 

 

[M204ever]

Apollo,

it appears that the engine shock mounts "settled down" and lowering the plenum. Check the engines position. There is an impressive topic within one of the earlier mooney flyer magazines about that.

I shimmed the mounts as well after reading it to re-adjust the engines center position within the cowling. Note that the adjustment of the throttle and mixture cable will change, too. And it is advisable to check any interference between the engine and the firewall forward equipment after doing it.

[Apollo]

Appears in what way? 

 

I will have it checked in the next few hours when its back at home base.